The invention relates to document reproduction machines, in particular to those document reproduction machines operable in a duplex mode.
Prior document reproduction machines, such as convenience copiers, have operated in both a simplex and duplex mode. Most copiers operable in both modes often have an interim storage unit termed a "duplex" tray or "auxiliary" tray for temporarily storing the partially reproduced copies; i.e., those copies have an image impressed on but one side. Upon completion of the production of the single-image interim duplex copies, a second original, or the opposite side of an original, is placed upon a platen for reproduction on the second side of the partially reproduced copies. Then, a second run of the copier is initiated wherein the copies in the interim storage unit are transferred through the reproduction process for receiving an image on the second-side. Then, the completed duplex copies are transferred to an output unit which may include a single tray or a collator. Accordingly, duplex copying machines have provisions for directing copies from the copy reproduction process to either the output portion or to the interim storage unit (for receiving the partially reproduced copies). All copies of one original image are termed a copy set. It is desired to have all copy sets in the output portion.
In producing two-sided copies in the duplex mode, a problem arises when there is an odd number of images to be copied. In such an instance, the last copy set of the duplex run resides in the interim storage unit and not in the normal output portion of the machine. Of course, if there is an even number of images, then all copy sets will be in the output portion.
Prior machines have permitted the last copy set to remain in the interim storage means requiring an operator to open the machine and remove the last copy set from the machine and then combine that last copy set with the previous copy sets already in the output portion. The above operator action is quite simple if the machine is in a noncollate mode or does not have a collator. However, if each copy set has up to 100 copies and a collator is in the output portion, then the operator must hand collate all 100 copies of the last copy set with the previously automatically collated copy sets.
To avoid the hand collation, it is possible in some copy machine to initiate an additional copy run whereat the reverse side of the platen is copied on the back side of the copies in the last copy set. This may result in pictures of transport wheels and the like being impressed upon the back side of the last copy set, which may be objectionable in some copy production. This action may also result in graying or other marks being imposed on the back side of the copies in the last copy set. In those machines charging the user by the number of images produced, the latter requires an additional charge for completing the run automatically. That is, the user is charged for running the last copy set through the machine even though the user desires no image to be put on the back side of the copies of the last copy set.
All of the above actions in handling an odd number original duplex copy run require thoughtful action on the part of the operator. For convenience purposes, it is desirable to minimize such action by the operator by making the document reproduction machine as fully automatic as possible. Such ease of operation facilitates greater throughput of the document reproduction machine.